Carbon nitride thin films were deposited on silicon wafers by pulsed KrF excimer laser (wavelength 248 nm, duration 23 ns) ablation of graphite with assistance of nitrogen ion beam bombardment. X-ray photoelectron spectroscopy, Raman spectroscopy, and ellipsometry were used to identify the binding structure, nitrogen content, and optical properties of the deposited thin films. The influence of the nitrogen ion beam energy on the compositional, electronic, and optical properties of the deposited thin films was investigated. The thin films deposited with nitrogen ion bombardment had an N/C ratio of 0.43. Raman spectroscopy measurements indicated the formation of CN triple bonds in the deposited thin films. The optical band gap Eopt was observed to decrease with the nitrogen ion energy. A nitrogen ion energy between 50 and 100 eV was deduced to be the optimal condition for depositing the carbon nitride thin films.